When an infusion operation such as a dripping infusion is done from a medical bag (first medical storage) for storing therein with medicines (first medicines) such as a liquid glucose and physiological saline, et al, a situation may occur that an addition (co-infusion) of different medicines (second medicines) such as vitamins to the medical bag is needed. Such a medical bag for infusion is formed as a bag from a flexible plastic film such as polyethylene, the medical bag having a sealed structure of an outlet port, which is provided with a plug made of an elastic material such as a rubber (first rubber plug). A co-infusion container (second medical storage) for storing therein with medicines for co-infusing operation with the medical bag is formed as a rigid plastic mold body and is provided with a rubber plug (second rubber plug) for sealing an injection port (co-infusion port) of a needle shape. Under un-wrapped condition of the second rubber plug, the needle shaped injection port of the second medical storage pierces the first rubber plug, which causes the medicine(s) in second medical storage medicine to be introduced into the first medical storage for obtaining co-infusion operation. As a system of such a principle of transportation, a relatively movable structure of a body (cylindrical portion) of a needle shaped injection port of the second medical storage (co-infusion container) is proposed. In this structure, when the needle shaped injection port of the second medical storage (co-infusion container) pierces the first rubber plug sealing the first medical storage, the second rubber plug sealing the second medical storage is broken, which allows the co-infusion process to be commenced. See patent publication No. 1.
Patent Publication No. 1: Japanese Examined Patent Publication No. 6-59302